Dr. James Thomka

Dr. James Thomka

Title: Assistant Professor of Instruction
Dept/Program: Geosciences
Office: Crouse Hall 62
Phone: 330 972-5749
Fax: 330 972-7611
Email: jthomka@uakron.edu
Website: /geology/

Research Accomplishments


My research falls within the broad fields of paleontology and stratigraphy, with an emphasis on deep-time interactions between organisms and their physical environment. This encompasses studies into the preservation, ecology, and biology of fossil organisms (and occasionally modern representatives), documentation of trace fossils and sedimentary properties of the units within which fossil data were derived, and high-resolution stratigraphic analysis of the successions comprising studied intervals. These results form the framework for interpretation of broader linkages between the biosphere and climatic-oceanographic-tectonic systems.

Current Research

Active research areas include: 1) utilizing echinoderm preservation as a tool in paleoenvironmental reconstruction; 2) interpreting the distribution and functional morphology of organismal attachment structures; 3) understanding patterns of marine authigenesis, particularly the stratigraphical, geochemical, and preservational significance of hardground surfaces and concretions; 4) using the trace fossil record to recognize biotic interactions and improve paleoenvironmental interpretations; and 5) enhancing sequence stratigraphic models through incorporation of paleobiological, stable isotopic, and magnetic susceptibiligy data.

Courses Taught

100: Earth Science

101: Introductory Physical Geology

102: Introductory Historical Geology

105: Geology for Engineers

121: Dinosaurs

122: Mass Extinctions and Geology

360: Paleobiology

453/553: Geology Field Camp I


(*asterisk denotes supervised undergraduate student co-author)

Thomka, J.R., under review, Plant or animal, terrestrial or marine? Thoughts on specimen curation in university palaeontological teaching collections based on an example from Ohio, USA: The Geological Curator, v. 10.

Thomka, J.R., Brett, C.E., and *List, D.A., under revision, Magnetic susceptibility of the latest Telychian-early Sheinwoodian (middle Silurian) succession of southeastern Indiana and northern Kentucky: Implications for stratigraphic interpretation of diagenetically altered units: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 522.

Thomka, J.R., and *Eddy, D.B., in press, Notes on additional material associated with the type specimens of Diphuicrinus ohioensis (Echinodermata: Crinoidea) from the Middle Pennsylvanian of southeastern Ohio: Ohio Journal of Science, v. 118.

Thomka, J.R., Sullivan, N.B., and Brett, C.E., 2018, Arthrophycus as a mimic of crinoid column impressions in the Lower Silurian of central Kentucky, USA: Lethaia, v. 51, p. 96-101.

Thomka, J.R., and Brett, C.E., 2017, Insights into the taxonomy and paleoecology of the ‘bead bed’ crinoid (Echinodermata: Crinoidea) based on new material from the Lower Silurian Brassfield Formation of east-central Kentucky: Palaios, v. 32, v. 762-768.

Brett, C.E., and Thomka, J.R., 2017, Fossil echinoderms of the middle Silurian in North America: An age of crinoids and “anachronistic” faunas: Mid-American Paleontological Society Exposition Digest, v. 40, p. 97-126.

Thomka, J.R., and Brett, C.E., 2017, The holdfast of Finitiporus boardmani (Echinodermata: Diploporita) in the Silurian Massie Formation of the Cincinnati Arch region, USA: Swiss Journal of Palaeontology, v. 136, p. 365-368.

Deline, B., and Thomka, J.R., 2017, The role of preservation on the quantification of morphology and patterns of disparity within Paleozoic echinoderms: Journal of Paleontology, v. 91, p. 618-632.

Sullivan, N.B., McLaughlin, P.I., Brett, C.E., Cramer, B.D., Kleffner, M.A., Thomka, J.R., and Emsbo, P., 2016, Sequence boundaries and chronostratigraphic gaps in the Llandovery of Ohio and Kentucky: The record of Early Silurian paleoceanographic events in east-central North America: Geosphere, v. 12, p. 1813-1832.

Thomka, J.R., Bantel, T.E., and *Tomin, M.J., 2016, Unusual preservation of the trace fossil Conostichus in middle Silurian carbonate facies of Indiana, USA: Canadian Journal of Earth Sciences, v. 53, p. 802-807.

Aucoin, C.D., Brett, C.E., Dattilo, B.F., and Thomka, J.R., 2016, Sequence stratigraphic model for repeated “butter shale” Lagerstätten in the Ordovician (Katian) of the Cincinnati, Ohio region, USA: Canadian Journal of Earth Sciences, v. 53, p. 763-773.

Thomka, J.R., Brett, C.E., *Young, A.L., Bantel, T.E., and Bissett, D.L., 2016, Taphonomy of ‘cystoids’ (Echinodermata: Diploporita) from the Napoleon quarry of southeastern Indiana, USA: The Lower Silurian Massie Formation as an atypical Lagerstätte: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 443, p. 263-277.

Brett, C.E., Thomka, J.R., Schwalbach, C.E., Aucoin, C.D., and Malgieri, T.J., 2015, Faunal epiboles in the Upper Ordovician of north-central Kentucky: Implications for high-resolution sequence and event stratigraphy and recognition of a major unconformity: Palaeoworld, v. 24, p. 149-159.

Thomka, J.R., and Brett, C.E., 2015, Palaeontological and sedimentological effects of micro-bioherms in the Middle Silurian Massie Formation of southeastern Indiana, USA: Lethaia, v. 48, p. 172-187.

Brett, C.E., Malgieri, T.J., Thomka, J.R., Aucoin, C.D., Dattilo, B.F., and Schwalbach, C.E., 2015, Calibrating water depths of Ordovician communities: Lithological and ecological controls on depositional gradients in Upper Ordovician strata of southern Ohio and north-central Kentucky, USA: Estonian Journal of Earth Sciences, v. 64, p. 19-23.

Thomka, J.R., and Brett, C.E., 2015, Paleoecology of pelmatozoan attachment structures from a hardground surface in the middle Silurian Massie Formation, southeastern Indiana: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 420, p. 1-12.

Thomka, J.R., Malgieri, T.J., and Brett, C.E., 2014, A swollen crinoid pluricolumnal from the Upper Ordovician of northern Kentucky, USA: The oldest record of an amorphous paleopathologic response in Crinoidea?: Estonian Journal of Earth Sciences, v. 63, p. 317-322.

Thomka, J.R., and Brett, C.E., 2014, Taphonomy of diploporite (Echinodermata) holdfasts from a Silurian hardground, southeastern Indiana, United States: Palaeoecologic and stratigraphic significance: Geological Magazine, v. 151, p. 649-665.

Thomka, J.R., and Motz, G.J., 2014, First report of Silurian crinoid columnals with tetralobate and hexalobate lumen structures: GFF, v. 136, p. 266-269.

Brett, C.E., Thomka, J.R., Sullivan, N.B., and McLaughlin, P.I., 2014, Anatomy of a compound sequence boundary: A basal Silurian karstic unconformity in the Cincinnati Arch region: GFF, v. 136, p. 42-47.

Thomka, J.R., and Brett, C.E., 2014, Diploporite (Echinodermata, Blastozoa) thecal attachment structures from the Silurian of southeastern Indiana: Journal of Paleontology, v. 88, p. 179-186.

Thomka, J.R., and Lewis, R.D., 2013, Siderite concretions in the Copan crinoid Lagerstätte (Upper Pennsylvanian, Oklahoma): Implications for interpreting taphonomic and depositional processes in mudstone successions: Palaios, v. 28, p. 697-709.

Brett, C.E., and Thomka, J.R., 2013, Fossils and fossilisation: eLS: Citable Reviews in the Life Sciences, 12 p.

Brett, C.E., Cramer, B.D., McLaughlin, P.I., Kleffner, M.A., Showers, W.J., and Thomka, J.R., 2012, Revised Telychian-Sheinwoodian (Silurian) stratigraphy of the Laurentian mid-continent: Building uniform nomenclature along the Cincinnati Arch: Bulletin of Geosciences, v. 87, p. 733-753.

Thomka, J.R., Mosher, D., Lewis, R.D., and Pabian, R.K., 2012, The utility of isolated crinoid ossicles and fragmentary crinoid remains in taphonomic and paleoenvironmental analysis: An example from the Upper Pennsylvanian of Oklahoma, United States: Palaios, v. 27, p. 465-480.

Thomka, J.R., Lewis, R.D., Mosher, D., Holterhoff, P.F., *León y León, I.A., and Pabian, R.K., 2011, Microstratigraphy and comparative taphonomic analysis of the upper core shale of a Pennylvanian cyclothem: Keys to the recognition of subtle cyclic deposition: Gulf Coast Assocation of Geological Societies Transactions, v. 61, p. 463-481.

Thomka, J.R., Lewis, R.D., Mosher, D., Pabian, R.K., and Holterhoff, P.F., 2011, Genus-level taphonomic variation within cladid crinoids from the Upper Pennsylvanian Barnsdall Formation, northeastern Oklahoma: Palaios, v. 26, p. 377-389.

Thomka, J.R., and Marzen, L.J., 2009, Treefall evidence for high wind events at Hawn State Park, St. Francois Mountains, Missouri: A case study in selective field data collection: Papers of the Applied Geography Conferences, v. 32, p. 173-180.


  • PhD, 2015, University of Cincinnati (Cincinnati, Ohio)

  • Dissertation: Dynamic Linkages between Stratigraphy, Climate, Oceanography, and Biotic Events in the Middle Silurian of Eastern Laurentia

  • MS, 2010, Auburn University (Auburn, Alabama)

  • Thesis: Genesis and Taphonomy of a Crinoid Lagerstätte in the Upper Pennsylvanian Barnsdall Formation of Northeastern Oklahoma

  • BS,2008, University of Tennessee—Martin (Martin, Tennessee)

  • Thesis 1: Siderite Concretions of the Upper Cliff Coal Interval (Pennsylvanian: Westphalian A): Fossil Content and Paleoenvironmental Implications
  • Thesis 2: Diagenesis and Morphology of Unusual Stromatolites in the Upper Cambrian Copper Ridge Dolomite, Cherokee Lake, East Tennessee